Adsorption of Chromium (VI) From Water Solution onto Organobentonite,

R. Leyva Ramos, A. Jacobo-Azuara, Oliva L. Torres- Rivera, R.M. Guerrero Coronado, M.S Berber- Mendoza y P. Alonso-Dávila,
J. Environ. Eng. Manage. 18(5) 311-317., 2008.


The organobentonite was prepared by adsorbing the cationic surfactant hexadecyltri- methylammonium bromide on the external surface and interlayer spacing of the bentonite. The adsorption equilibrium data of Cr(VI) from an aqueous solution on an organobentonite was determined in a batch adsorber. The effects of the temperature and pH on the adsorption isotherm were investigated in this work. The Cr(VI) adsorption capacity of organobentonite showed a maximum at pH = 5 and diminished increasing pH from 5 to 12 and decreasing pH from 5 to 4. Increasing the temperature from 15 to 35 °C, the adsorption capacity was reduced since the adsorption of Cr(VI) on the organobentonite was exothermic. The isosteric heat of adsorption was - 32.9 kJ mol-1 for a Cr(VI) uptake of 10 mg g-1. The magnitude of the heat of adsorption was near the magnitude of a chemical reaction. Desorption studies showed that Cr(VI) was irreversibly adsorbed on organobentonite, corroborating that Cr(VI) was chemisorbed on the organobentonite.